Quantum Technique for Gravitational Wave Detection

• A new NASA Institute for Advanced Concepts (NIAC) grant is funding a team led by Paul Stankus at Brookhaven National Laboratory to develop a quantum-based gravitational wave detector.
• The proposed method utilizes the Hanbury Brown and Twiss (HBT) effect to eliminate the need for physical laser links between spacecraft.
• By observing the astrometric "wobble" of distant stars caused by gravitational waves, the system aims to close the sensitivity gap between current Pulsar Timing Arrays and the upcoming LISA mission.

The Engineering Gap

• Ground-based detectors like LIGO sense high-frequency waves (10-10,000 Hz).
• Pulsar Timing Arrays (PTAs) track nano-Hertz background hums over decades.
• The upcoming LISA mission will detect milli-Hertz waves from supermassive black holes.
• A significant sensitivity gap exists in the micro-Hertz range because space-based interferometers currently require difficult-to-maintain, ultra-precise laser links between mirrors spaced millions of kilometers apart.

The Quantum Solution

• The team's "two-photon amplitude interferometer" uses two independent spacecraft in free-fall orbits.
• The craft observe identical stars simultaneously, recording arrival times of individual photons with high-precision timestamps.
• Back on Earth, supercomputers analyze the data for "quantum bunching"—microscopic correlations—to calculate the phase interference of the starlight without a physical optical connection.
• If a coordinated pattern of star wobbles is detected across multiple stellar observations, it signifies the passage of a gravitational wave.

Development Status

• The research team successfully demonstrated the concept in a lab-based, tabletop version in 2023.
• The current 9-month NIAC grant focuses on proving that this technology can be scaled for deployment on satellites operating in space.